Synchronizer

ABSTRACT

A synchronizer ( 10 ) with improved blockers ( 41 ) and pre-energizers ( 43 ). The synchronizer includes blocker pins ( 40 ) that extend axially through blocker openings ( 41   a ) in a radially extending shift flange ( 32 ) and split pin pre-energizers ( 42 ) having pairs of members ( 44 ) extending axially through pre-energizer openings ( 43   a ) in the flange. The openings ( 41   a   ,43   a ) are defined by blocker and pre-energizer rings ( 41,43 ) respective disposed in openings ( 32   a   ,32   b ) in the flange.

FIELD OF THE INVENTION

This invention relates to a pin-type synchronizer for a transmission.More specifically, this invention relates to an improved blocker and/orpre-energizer means for such a synchronizer.

BACKGROUND OF THE INVENTION

Synchronizers of the general type disclosed herein are well known in theprior art as may be seen by reference to U.S. Pat. Nos. 5,339,936 and4,018,319 and GB Patent 1,473,844, the disclosures of these patents areincorporated herein by reference. Synchronizers of the type disclosedherein generally include jaw clutches and blocker pins that extendaxially from a friction member through first openings in a radiallyextending flange. The pins include angled blocker shoulders that engageangled blocker shoulders defined about the openings to preventasynchronous engagement of the jaw clutches. These synchronizers may beof the double acting or the single acting as shown in theabove-mentioned patents. Some of these synchronizers may includepre-energizers of the so-called split pin type in lieu of pre-energizersof the type in U.S. Pat. No. 5,092,439. Pairs of the split pins extendthrough second openings in the flange and interspaced between the firstopenings. Springs bias the pairs of split pins apart to ensureengagement of angled pre-energizer shoulders defined by the split pinsand with angled pre-energizer shoulders defined about the secondopenings. The engaged shoulders effect engagement of the frictionclutches in response to initial engaging movement of the shift flange.

In the event of wear of the angled shoulders defined about the firstand/or second openings, the shift flange needs to be replaced to ensureproper operation of the blocking and/or pre-energizer functions.Further, when the same basic synchronizer is used in different positionsin a transmission or in different transmissions, at may requiredifferent shoulder angles, whereby requiring a large inventory of shiftflanges that differ only by shoulder angle.

SUMMARY OF THE INVENTION

An object of this invention is to provide improved blocker and/orpre-energized shoulders of a synchronizer.

Another object of this invention is to provide improved pre-energizersplit pins for a synchronizer

According to a feature of this invention, a synchronizer is provided fora first drive secured against axial movement relative to a second drivehaving an axis about which the drives rotate. The synchronizercomprises: A first jaw means is rotatable with the second drive and isaxially moveable into engagement with a second jaw means for positivelyconnectively connecting the drives. A first friction means is axiallymoveable into engagement with a second friction means for synchronizingthe drives. A radially extending flange is rotatable with the seconddrive. Blocker openings are circumferentially spaced apart and extendingaxially through the flange. Circumferentially spaced apart blocker pinsare axially extending rigidly from the first friction means and a one ofeach pins is slidably received in an associated one of each of theblocker openings. Each blocker pin has a blocker shoulder engagable witha blocker shoulder disposed about the associated blocker opening forpreventing asynchronous engagement of the first and second jaw means.

The improvement comprises blocker rings each having an innercircumferential portion defining one of the blocker openings and havingan outer circumferential portion axially fixed in an innercircumferential portion of a flange opening extending axially throughthe flange.

According to another feature of the invention, a double actingsynchronizer clutch includes: First and second axially movable frictionmeans are rigidly connected together about a rotational axis in axiallyspaced relation on opposite sides of an axially movable, radiallyextending flange. A plurality of circumferentially spaced apartpre-energizer openings extend axially through the flange. A split pinassembly includes a pair of members biased apart by a spring assemblyand extending axially through each pre-energizer opening and between thefirst and second friction means for effecting axial movement of thefriction means in response to initial axial movement of the flange froma neutral position. Each pair of members defines a generally cylindricalouter surface with a radially outwardly open annular detent groove forreceiving an inner circumferential portion of one of the pre-energizeropenings.

The improvement comprises pre-energizer rings that each have an innercircumferential portion defining one of the per-energizer openings andan outer circumferential portion axially fixed in an innercircumferential portion of a flange opening extending axially throughthe flange.

BRIEF DESCRIPTION OF THE DRAWINGS

The synchronizer assembly of the invention is shown in the accompanyingdrawings in which:

FIG. 1 is a vertically sectioned view of a double acting synchronizerhaving replaceable rings defining angled blocker and pre-energizershoulders, and

FIGS. 2-5 are enlarged views of the rings.

DETAILED DESCRIPTION OF THE DRAWINGS

Looking now at the drawings, therein is a simplified illustration of agear and shaft assembly 10 for an otherwise unshown transmission of thetype intended for use in a land vehicle, particularly of the type usedin medium and heavy duty trucks. However, assembly 10 may be used inother applications. The assembly includes a drive or shaft 12 mountedfor rotation about a central axis 12 a in unshown manner, spaced apartdrives or ratio gears 14,16 rotatably supported on the shaft and securedagainst axial movement relative to the shaft by annular thrust members18,20 affixed to the shaft in known manner, and a double-acting pin-typesynchronizer 22. When assembly 10 is part of a twin countershafttransmission, such as disclosed in U.S. Pat. Nos. 3,648,546 and4,788,889, which patents are incorporated herein by reference, teeth 14a,16 a on the gears will be in constant mesh with engine driven gears15,17 on countershafts, shaft 12 will be connected to or selectivelyconnectable to a load, and shaft 12 will be free to move somewhatradially as is well known in the prior art. Herein gear 14 represents alower speed ratio gear than does gear 16; both may be up and downshifted into. In some aspects of the invention synchronizer 22 may be ofthe single acting type as shown in previously mentioned patent GB1,473,844.

The synchronizer mechanism 22 includes annular friction members or rings24,26 and annular jaw clutch members 14 b,16 b affixed to gears 14,16, ajaw clutch or collar member 28 having internal spline teeth 28 aslidably mating with external spline teeth 12 b integrally formed withthe shaft or otherwise affixed thereto, a radially extending shiftflange 32, having a radially inner extent affixed to jaw clutch member28, annular friction members or rings 36,38 rigidly secured together bythree circumferentially spaced apart blocker pins 40 extending axiallyand rigidly from each of the friction members and through blockeropenings 41 a in the flange, and three circumferentially spaced apartpre-energizer or split pin assemblies 42 extending axially between thefriction members and through pre-energizer openings 43 a inner spacedbetween blocker openings 41 a. Jaw clutch member 28 includes externaljaw teeth 28 b,28 c which respectively engage jaw teeth 14 b,16 b.Blocker pins 40 and split pin assemblies 42 may be more or less innumber than disclosed herein. Blocker openings 41 a and pre-energizeropenings 43 a are defined by blocker and pre-energizer rings 41,43explained further hereinafter. Flange 32 may be mounted for limitedrotation relative to shaft 12 as taught in U.S. Pat. No. 5,769,198.

As is readily seen, friction members 24,36 and 26,38 pair up to definefriction clutches for synchronizing the gears to the shaft prior toengagement of the jaw clutches. Cone clutches are preferred; however,other types of friction clutches may be used. Friction members 24,26 maybe affixed to the associated gears in any of several known ways.Friction members 24,26 have internal cone friction surfaces 24 a,26 awhich respectively mate with external cone friction surfaces 36 a,38 a.Members 24,26 and 36,38 also are respectively referred to assynchronizer cups and rings. A wide range of cone angles may be used.The friction surfaces 36 a,38 a and/or 24 a,26 a may be defined by anyof several known materials.

Each pin 40 includes major diameter portions 40 a having diametersslightly less than the diameter of blocker openings 41 a, a reduceddiameter or groove portion 40 b spaced between friction rings 36,38(herein midway), and angled blocker shoulders 40 c,40 d extendingradially outward from the pin axis and axially away from each other atangles relative to a line normal to the pin axis. The grooved portions,when disposed within their respective blocker openings 41 a, allowlimited rotation of the rigid friction rings and pin assemblies relativeto the flange to effect engagement of the pin blocker shoulders withangled blocker shoulders 41 b,41 c defined about ring openings 41 a. Theblocker shoulders, when engaged, prevent asynchronous engagement of thejaw clutch members.

Each split pin assembly 42, includes a pair of split pins orsemi-cylindrical members 44 having a major diameter less than thediameter of pre-energizer openings 43 a when squeezed together,semi-annular grooves 44 a with angled pre-energizer shoulders 44 b and aleaf spring assembly 46 sandwiched between mutually facing innersurfaces of members 44 for biasing the annular grooves apart to engageshoulders 44 b with angled pre-energizer shoulders 43 b,43 c formedabout opposite ends of openings 43 a. Ends 44 c,44 d of the members 44abut friction rings 36.

While flange 32 is in the neutral position, the friction surfaces of thecone clutches are spaced apart. When it is desired to couple either gearto the shaft, an appropriate and unshown shift mechanism connected tothe outer periphery of flange 32 in known manner moves the flangeaxially along the axis of shaft 12 either left to couple gear 14 orright to couple gear 16. The shift mechanism may be manually moved by avehicle operator through a linkage system, may be selectively moved byan actuator, or may be moved by means which automatically initiate shiftmechanism movement and which also controls the magnitude of the forceapplied by the shift mechanism. When the shift mechanism is manuallymoved, the force is proportional to the force applied by the operator toa shift lever.

Initial axial rightward movement of flange 32 by the shift mechanismengages pre-energizer shoulders 43 c with pre-energizer shoulders 44 bto effect movement of friction ring surface 38 a into engagement withfriction surface 26 a. The initial engagement force of friction surfaces38 a,26 a is, of course, a function of the force of spring assemblies 46and the angles of pre-energizes shoulders 43 c,44 b. The initialfrictional engagement, provided an asynchronous condition exists,produces an initial cone clutch engaging force and synchronizing torquewhich ensures limited relative rotation between flange 32 and theengaged friction ring, and hence, movement of the reduced diameter pinportions 40 b to the appropriate sides of the blocker openings 41 a toprovide engagement of pin blocker shoulders 40 c with blocker shoulders41 b. When the blocker shoulders are engaged, full operator shift forceon flange 32 is transmitted to friction ring 38 via the blockershoulders, whereby the cone clutch is engaged by the full force of theoperator shift force. Since the blocker shoulders are disposed at anglesrelative to the axial direction of operator shift force, they produce acounter force or unblocking torque which is counter to the synchronizingtorque from the cone clutch but of lesser magnitude during asynchronousconditions. As substantial synchronism is reached, the synchronizingtorque drops below the unblocking torque, whereby the blocker shouldersmove the pins into concentric relation with blocker openings 41 a toallow continued axial movement of the flange and engagement of theexternal jaw teeth 28 b of jaw member 28 with internal jaw teeth of jawmember 16 b.

Looking now mainly at FIGS. 2-5, blocker and pre-energizer rings 41,43may be formed from any material having sufficient strength and wearresistance, for example, metal, plastic, ceramic, etc. Ring 41 is shownin FIGS. 2 and 3 formed of a plastic material and ring 43 is shown inFIGS. 4 and 5 formed of metal. Rings 41,43 include inner circumferentialportions defining openings 41 a,43 a having shoulders 41 b,41 c and 43b,43 c on opposite sides, outer circumferential portions 41 d,43 dsecured against axial movement in flange openings 32 a,32 b, and openarc portions 41 e,43 e. The outer circumferential portions of the ringsinclude shoulders 41 f,43 f defined by recesses that receive ring likeportions that extend radially inward from flange openings 32 a,32 b.Other means may be used to secure the rings in openings 32 a,32 b. Theopen arc portions facilitate installation of the rings in openings 32a,32 b by flexibly reducing the diameter of the outer circumferentialportions of the rings. Axially extending slits 41 g,43 g in the outercircumferential portions of the rings may be used to increase ringflexibility.

Rings 41,43 provide a simple and inexpensive way to repair or replaceworn blocker and/or pre-energizer shoulders without need to replace theshift flange. In some cases repair may by made be merely rotating therings enough the present unworn shoulders. Additionally, split pins 44may be formed of plastic or ceramic materials, which in many cases arelighter in weight and less in cost. Further, the rings may be formed ofmultiple pieces to simplify plastic or metal injection of the pieces.

The synchronizer embodiment herein has been disclosed for illustrativepurposes. Many variations and modifications of the disclosed embodimentare believed to be within the spirit of the invention. The followingclaims are intended to cover the inventive portion of the disclosedembodiment and variations and modifications believed to be within thespirit of the invention.

What is claimed is:
 1. A synchronizer for a first drive secured againstaxial movement relative to a second drive having an axis about which thedrives rotate, the synchronizer comprising: first jaw means rotatablewith the second drive and axially moveable into engagement with a secondjaw means for positively connecting the drives; first friction meansaxially moveable into engagement with second friction means forsynchronizing the drives; a radially extending flange rotatable with thesecond drive; blocker openings circumferentially spaced apart andextending axially through the flange; and circumferentially spaced apartblocker pins axially extending rigidly from the first friction means anda one of each pins slidably received in an associated one of each of theblocker openings, each blocker pin having a blocker shoulder engagablewith a blocker shoulder disposed about the associated blocker openingfor preventing asynchronous engagement of the first and second jawmeans; the improvement comprising: blocker rings each having an innercircumferential portion defining one of the blocker openings and havingan outer circumferential portion axially fixed in an innercircumferential portion of a flange opening extending axially throughthe flange.
 2. The synchronizer of claim 1, further including a thirddrive axially spaced from the first drive and secured against axialmovement relative to the second drive for rotation about the axis; thirdjaw means rotatable with the second drive and axially moveable intoengagement with a fourth jaw means for positively connecting the secondand third drives; third friction means axially moveable into engagementwith fourth friction means for synchronizing the second and thirddrives; and the blocker pins axially extending rigidly to the thirdfriction means, and each blocker pin having another blocker shoulderengagable with another blocker shoulder disposed about the associatedblocker opening for preventing asynchronous engagement of the third andfourth jaw means.
 3. The synchronizer of claim 1, wherein: each blockerring outer circumferential portion and each flange opening innercircumferential portion have axially engagable shoulders for preventingaxial movement of the blocker rings relative to the flange; and eachblocker ring has an open arc portion to facilitate installation of theblocker rings in the flange openings by flexible reduction of thediameter of the outer circumferential portion of each blocker ring. 4.The synchronizer of claim 2, wherein: each blocker ring outercircumferential portion and each flange opening inner circumferentialportion have axially engagable shoulders for preventing axial movementof the blocker rings relative to the flange; and each blocker ring hasan open arc portion to facilitate installation of the blocker rings inthe flange openings by flexible reduction of the diameter of the outercircumferential portion of each blocker ring.
 5. The synchronizer ofclaim 2, further including: circumferentially spaced apart pre-energizeropenings extending axially through the flange and interspaced betweenthe blocker openings; a split pin assembly including a pair of membersbiased apart by a spring assembly and extending axially through eachpre-energizer opening and between the first and third friction means foreffecting axial movement of the first and third friction means inresponse to initial axial movement of the flange from a neutralposition, and each pair of members defining a generally cylindricalouter surface with a radially outwardly open annular detent groove forreceiving an inner circumferential portion of one of the pre-energizeropenings; and pre-energizer rings defining the inner circumferentialportion of each pre-energizer opening and having an outercircumferential portion axially fixed in an inner circumferentialportion of a second flange opening extending axially through the flange.6. The synchronizer of claim 1, wherein: each ring is formed of a metalmaterial.
 7. The synchronizer of claim 1, wherein: each ring is formedof a plastic material.
 8. The synchronizer of claim 2, wherein: eachring is formed of a metal material.
 9. The synchronizer of claim 2,wherein: each ring is formed of a plastic material.
 10. The synchronizerof claim 3, wherein: each ring is formed of a metal material.
 11. Thesynchronizer of claim 3, wherein: each ring is formed of a plasticmaterial.
 12. The synchronizer of claim 4, wherein: each ring is formedof a metal material.
 13. The synchronizer of claim 4, wherein: each ringis formed of a plastic material.
 14. The synchronizer of claim 5,wherein: each ring is formed of a metal material.
 15. The synchronizerof claim 5, wherein: each ring is formed of a plastic material.
 16. Adouble acting synchronizer clutch including: first and second axiallymovable friction means rigidly connected together about a rotationalaxis in axially spaced relation on opposite sides of an axially movable,radially extending flange; a plurality of circumferentially spaced apartpre-energizer openings extending axially through the flange; a split pinassembly including a pair of members biased apart by a spring assemblyand extending axially through each pre-energizer opening and between thefirst and second friction means for effecting axial movement of thefriction means in response to initial axial movement of the flange froma neutral position, and each pair of members defining a generallycylindrical outer surface with a radially outwardly open annular detentgroove for receiving a inner circumferential portion of one of thepre-energizer openings; characterized by: pre-energizer rings eachhaving an inner circumferential portion defining one of thepre-energizer openings and having an outer circumferential portionaxially fixed in an inner circumferential portion of a flange openingextending axially through the flange.
 17. The synchronizer of claim 16,wherein: each pre-energizer ring outer circumferential portion and eachflange opening inner circumferential portion have axially engagableshoulders for preventing axial movement of the pre-energizer ringsrelative to the flange; and each pre-energizer ring has an open arcportion to facilitate installation of the pre-energizer rings in theflange openings by flexible reduction of the diameter of the outercircumferential portion of each pre-energizer ring.
 18. The synchronizerof claim 16, wherein: each ring is formed of a metal material.
 19. Thesynchronizer of claim 16, wherein: each ring is formed of a plasticmaterial.
 20. The synchronizer of claim 17, wherein: each ring is formedof a metal material.
 21. The synchronizer of claim 17, wherein: eachring is formed of a plastic material.
 22. The synchronizer of claim 16,wherein: each pair of members is formed of a plastic material.
 23. Thesynchronizer of claim 19, wherein: each pair of members is formed of aplastic material.